Union members compete to punch drunkards (7)

I believe the answer is:

soviets

'union members' is the definition.
(residents of the Soviet Union)

'compete to punch drunkards' is the wordplay.
'compete' becomes 'vie' ('vie' can be a synonym of 'compete').
'to punch' indicates putting letters inside.
'drunkards' becomes 'sots' ('sot' can be a synonym of 'drunkard').
'vie' going into 'sots' is 'SOVIETS'.

I've seen this clue in The Independent.

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